I. Field of the Invention
The present invention relates generally to floor treating machines such as burnishers, planetary grinders, polishers and floor scrubbers and, more particularly, to the construction of the pad driver used in such machines.
II. Discussion of the Prior Art
Many machines have been devised for grinding, burnishing, polishing and scrubbing concrete or stone floors to remove surface irregularities and to provide the floors with an attractive, usually shiny and even, appearance. The machines generally comprise a wheeled frame supporting an electric motor or a propane-fueled internal combustion engine having a vertically oriented drive shaft that extends through a top surface of a shroud. Beneath the shroud is one or more circular disks on which abrasive pads are affixed. The drive shaft of the motor extends through bearings in the shroud and is connected so as to spin the pad driving disks about vertical axis. See, for example, U.S. Pat. Nos. 4,715,087; 5,870,791; 7,563,156; and Published Application U.S. 2011/0300784. In each of these machines, the pad driver is planar, rigid and rotates about a vertical axis such that the abrasive pad(s) is/are parallel to the floor.
During operation on a newly installed concrete, marble or other stone floor, irregularities, such as low spots, high spots and ripples are often encountered. Because the prior art pad drivers are rigid, they are unable to follow the contour of the floor. This makes it difficult to achieve a smooth, even look to the floor surface and can greatly expand the time a worker needs to achieve a desired appearance.